Corrosion and scale
Causes of scale deposition in production wells
Change of thermobaric conditions (temperature, pressure)
Waters that have different salinity and come from different interlayers (layers) are mixed, which results in a change of the water mineral composition or oversaturation with salt-forming ions.
An effective way to prevent scale deposition and corrosion (“Squeeze“technology)
Squeezing of a number of reagents into the near-wellbore zone with a further gradual flowback during stimulation.
Target – 150 wells.
Squeezing sequence:
Cross-solvent – to raise the effectiveness of reagent adsorption and restore reservoir phasal permeability
Bactericide solution – to inhibit the development of sulphate-reducing bacteria and to lower the intensity of FeS formation
Scale inhibitor solution (corrosion inhibitor) – to prevent the deposits of a certain type of slightly soluble salt (CaSO4, CaCO3, BaSO4 and others ) or to inhibit corrosion
Potassium chloride solution – to squeeze reagents into the formation to the required depth
Equipment:
1 cementing unit CА-320 (units UNB-4, UNB-5)
A road tank АC-5, АC-8 (the quantity depends on the number of units required for a certain well)
The technology provides for the following:
a 3 to 8 time increase of the mean time to failure of ECP
Application of downhole dosing tanks to inhibit scale and paraffin deposition and corrosion.
The dosing tank filled with an inhibiting composition is placed under the submersible electric motor of the ESP unit.
The technology provides for the following:
- Prevents scale and paraffin deposition and corrosion in the submersible electric motor zone, working parts of the electric centrifugal pump and in the well lift;
- Mean time to failure twice as long and longer;
- Inhibition operation costs are lower compared to other protection methods.